In various printing technologies, marking material is applied to an intermediate imaging surface of a rotating structure, such as a belt or a drum. Print media are then pressed against the intermediate imaging surface to transfer the image from the intermediate imaging surface to the print media. In one example using phase change inkjet printing, ink is deposited to form an image on the surface of an imaging drum. A transfix roller presses the print media against the image-bearing drum surface to transfer the ink image from the drum surface to the print media to the print media.
By way of example, FIG. 9 shows a schematic view of a portion of an exemplary inkjet printing apparatus 10 of the prior art. The printing apparatus 10 is a phase change inkjet print mechanism. In a phase change inkjet printer, ink is delivered to the printer in a solid form. A melting device in the printer heats the solid ink to its melting temperature to form liquid ink, which is then delivered to an inkjet printhead 14. The inkjet printhead 14 ejects drops of the liquid ink from a plurality of inkjet inkjets onto an intermediate imaging surface 18, which is depicted as a liquid pre-coated rotating drum in the figure for purposes of illustration. After the printhead 14 forms the image on the surface of the intermediate imaging surface 18, a transfix mechanism moves a transfix roller 22 into engagement with the drum surface 18 as a media sheet 26 approaches the nip formed by the transfix roller 22 and the drum surface 18. As the media sheet travels through the nip in synchronization with the ink image on the surface 18, the image is transferred from the intermediate imaging surface 18 to the media sheet 26. This transfer process is called a transfix process because the image is simultaneously transferred and bonded (or fixed) to the media sheet 26. Other mechanisms are also known for transferring marking material images on intermediate imaging surfaces to media.
Sometimes ink at an inkjet nozzle of a printhead 14 can degrade with time. For example, aqueous ink can dry in an aperture and clog the inkjet. The drying of ink in an inkjet can occur because the inkjet has not been fired for some period of time. Loss of the inkjet can negatively affect the quality of printed images. To help prevent inkjets from clogging because ink dries in the inkjet, the inkjets in a printhead can be operated to eject ink in an effort to replace ink exposed to ambient conditions with ink from within the printhead. This ejected ink is not used to produce a printed image. Thus, while this process is useful, the ejected ink that is not part of an image needs to be removed without impacting the formation of subsequent ink images. Accordingly, a mechanism for collecting ink from inkjets that were operated to keep relatively fresh ink at the inkjet inkjets would be useful.